CRISPR technology has made it easier than ever both to engineer specific DNA edits and to perform functional screens to identify genes involved in a phenotype of interest. This blog post will discuss differences between these approaches, and provide updates on how best to design gRNAs.
Location and sequence are important considerations for designing your gRNAs. For indels, it's not so important what location in the gene you target, but it is important that your gRNA sequence is designed to be highly active and reduce off targets. For CRISPRa and CRISPRi, these considerations are of roughly equal importance (target should be near the TSS but you can worry less about sequence optimality because you generally have fewer sequences to choose from). Finally, for HDR, location is much more important because you have to target within ~30 nt of your proposed edit, which means there are so few gRNAs to choose from that sequence
